CVE-2023-42657 in WS_FTP Server
Summary
by MITRE • 10/25/2023
In WS_FTP Server version 8.7.0 prior to 8.7.4 and
version 8.8.0 prior to 8.8.2, a directory traversal vulnerability was discovered. An attacker could leverage this vulnerability to perform file operations (delete, rename, rmdir, mkdir) on files and folders outside of their authorized WS_FTP folder path. Attackers could also escape the context of the WS_FTP Server file structure and perform the same level of operations (delete, rename, rmdir, mkdir) on file and folder locations on the underlying operating system.
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Analysis
by VulDB Data Team • 10/25/2023
The vulnerability identified as CVE-2023-42657 represents a critical directory traversal flaw within WS_FTP Server software that affects versions prior to specific patched releases. This directory traversal vulnerability stems from inadequate input validation and path sanitization within the file operation handlers of the FTP server implementation. The flaw allows authenticated attackers to manipulate file system operations by crafting malicious path sequences that bypass the intended security boundaries of the WS_FTP server environment. The vulnerability specifically impacts both version 8.7.0 through 8.7.3 and version 8.8.0 through 8.8.1, creating a significant security gap that persists across multiple release branches of the software.
The technical exploitation of this vulnerability occurs through the manipulation of file operation commands such as delete, rename, rmdir, and mkdir functions. Attackers can leverage the flawed path resolution mechanism to escape the designated WS_FTP folder context and gain access to arbitrary locations within the underlying operating system. This occurs because the server fails to properly validate and sanitize user-supplied paths before executing file system operations, allowing attackers to append directory traversal sequences such as ../ or ..\ to access parent directories beyond the intended scope. The vulnerability essentially removes the containment boundaries that should restrict file operations to the designated FTP server directory structure, enabling attackers to perform destructive operations on system files and directories outside the authorized scope.
The operational impact of CVE-2023-42657 extends beyond simple unauthorized access to system resources, as it provides attackers with full control over file system operations within the compromised server environment. This vulnerability enables attackers to delete critical system files, rename important directories, create new directories in unauthorized locations, and remove existing directories, potentially causing system instability or complete service disruption. The ability to perform these operations at the underlying operating system level means that attackers can escalate their privileges and potentially compromise the entire server infrastructure, making this vulnerability particularly dangerous in enterprise environments where WS_FTP Server may be used for sensitive data transfers. The vulnerability aligns with CWE-22 directory traversal weakness and represents a significant deviation from the principle of least privilege in file system access control.
Security professionals should immediately implement mitigations including upgrading to WS_FTP Server versions 8.7.4 or 8.8.2, which contain the necessary patches to address the directory traversal vulnerability. Network segmentation and firewall rules should be implemented to restrict access to the FTP server from untrusted networks, while monitoring systems should be configured to detect unusual file system operations patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and the principle of containment in server-side applications, as outlined in the ATT&CK framework under the privilege escalation and persistence techniques. Organizations should also conduct thorough security assessments of all FTP server implementations and ensure that proper access controls and audit logging mechanisms are in place to detect and prevent unauthorized file system modifications. Regular vulnerability scanning and patch management processes should be enhanced to prevent similar issues in other server applications and ensure comprehensive protection against directory traversal attacks.